Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181956 AFDOKX Area Forecast Discussion National Weather Service New York NY 356 PM EDT Wed Apr 18 2018 .SYNOPSIS...
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Low pressure tracks across the Ohio Valley this evening and to just south of Long Island on Thursday. The deepening low then quickly exits into the Canadian Maritimes Thursday night through Friday. High pressure builds through the weekend and into early next week. Unsettled weather may return by the middle of next week as low pressure approaches.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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On the heels of a departing upper low across eastern Canada, a vigorous shortwave trough at the base of the upper trough will pivot across the area into Thursday. This will send low pressure over the Ohio Valley east tonight and then to the south of the area Thursday morning. Warm advection ahead of the system will result in increasing clouds this evening with light rain developing from west to east after midnight. Overnight lows will drop into the upper 30s across the interior and Pine Barrens region, and in the lower to mid 40s elsewhere.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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Periods of light rain will continue for much of the day Thursday with the highest probability being across the interior where the better thermal forcing will prevail. As low pressure pulls to the east by afternoon, wraparound light rain will continue, tapering off from west to east during the late afternoon/early evening hours. Rainfall totals for the event will range from about a tenth to a quarter inch, with the highest amounts across the interior. As the precipitation winds down, there is the possibility that a few snow flakes could mix in. It will be another unseasonably cold day with temperatures remaining in the 40s, and then dropping into the 30s Thursday night. Gusty NW winds up to 30 mph will develop behind the low late Thursday afternoon/early evening and continue through the overnight.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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Generally tranquil weather is expected during this time frame. Departing trough to the northeast makes slow progress, with upper level NW flow continuing across the northeast through the weekend. Ridge builds across the upper midwest and Great Lakes region, to the north of southern stream shortwave that passes from the Rockies through the southern states. The southern stream shortwave, along with northern stream energy will likely make progress toward the east coast Tuesday-Wednesday, potentially resulting in unsettled weather by mid week next week. Otherwise, dry conditions along with slightly below normal temperatures are anticipated.
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&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... A wave of low pressure approaches tonight, and passes over the region Thursday morning. VFR through midnight. Clouds thicken and lower overnight, falling to MVFR then eventually IFR by early Thursday morning. Ceilings will begin to improve back to VFR late in the 30 hour TAF sites. W winds around 15 KT with gusts 20-25 KT today. Winds then diminish early this evening becoming light and variable. Winds then become northwesterly by midday Thursday with gusts around 20-25kt. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Occasional gusts to 20 kt still possible from 22- 00z. KLGA TAF Comments: Occasional gusts to 20 kt still possible from 22- 00z. KEWR TAF Comments: Occasional gusts 16-19 kt still possible from 22- 00z. KTEB TAF Comments: Occasional gusts 16-19 kt still possible from 22- 00z. KHPN TAF Comments: Occasional gusts 16-19 kt still possible from 22-00z. KISP TAF Comments: Occasional gusts up to 20 kt still possible from 22-00z. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Thursday-Thursday night...IFR/MVFR in rain Thursday, rain/snow showers THU night. NW winds G20-30KT Thursday afternoon. .Friday...VFR. NW winds G25-30KT. .Saturday-Monday...VFR. && .MARINE...
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Lingering high seas on the ocean waters east Moriches Inlet will fall below SCA this evening. Wind and seas will subside tonight as low pressure approaches from the Ohio Valley and passes just south of the waters Thursday morning. As the low deepens heading up into the Canadian Maritimes Thursday night into Friday, near gale force gusts will develop on the waters Thursday evening. A moderate northwest pressure gradient should allow for SCA gusts 25- 30 kt to continue over the waters on Friday, before diminishing Friday night. The pressure gradient is forecast to relax over the waters this weekend, becoming light by Saturday night. As a result, sub Small Craft Advisory conditions are forecast over the waters around Long Island Saturday-Monday as high pressure builds closer.
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&& .HYDROLOGY...
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Rain amounts below a half inch are expected tonight through Thursday evening with no hydrologic impacts anticipated. Dry weather follows thereafter. There is the potential for significant rainfall mid week next week.
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&& .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 6 PM Thursday to 6 AM EDT Friday for ANZ330-335-338-340-345. Small Craft Advisory from 6 PM Thursday to noon EDT Friday for ANZ353-355. Small Craft Advisory until 11 PM EDT this evening for ANZ350.
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&& $$ SYNOPSIS...DW/PW NEAR TERM...DW SHORT TERM...DW LONG TERM...PW AVIATION...BC MARINE...DW/PW HYDROLOGY...DW/PW EQUIPMENT...//

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